Combustion-powered, fastener-driving tools, such as combustion-powered, nail-driving tools and combustion-powered, staple-driving tools are exemplified in Nikolich U.S. Pat. Re. No. 32,452, Nikolich U.S. Pat. Nos. 4,552,162, No. 4,483,474, and No. 4,403,722, and Wagdy U.S. Pat. No. 4,483,473.
Such a tool includes switches that must be closed to enable ignition of a combustible fuel in a combustion chamber of the tool. These switches include a head switch and a trigger switch. The head switch is closed by pressing a workpiece-contacting element, which is mounted operatively to a nosepiece of the tool, firmly against a workpiece. The trigger switch is closed by pulling a trigger, which is mounted operatively to a handle of the tool. An improved ignition system employing such head and trigger switches, for such a tool, is disclosed in Rodseth et al. U.S. Pat. No. 5,133,329.
As disclosed in the Nikolich patents noted above, it has been known to dispense the fuel volumetrically from a pressurized container, by means of a mechanical valve, when the workpiece-contacting element is pressed firmly against a workpiece. The mechanical valve enables a specific volume of the fuel to enter the combustion chamber. A pressurized container useful in such a tool is disclosed in Nikolich U.S. Pat. No. 5,115,944.
It has been found that when a tool of a different size or a combustible fuel having different properties is used, or when the tool is used at different conditions of ambient temperature or at a different altitude, it may be then necessary to employ a different valve enabling a different volume of the combustible fuel to enter the combustion chamber, so as to enable the tool to perform consistently.
There has been a need, to which this invention is addressed, for an improved system for controlling a combustible fuel entering the combustion chamber.